ALEXA JO DULING WILLIAMS MD
NPI 1972033652
Obstetrics & Gynecology in O Fallon, MO
About Alexa Jo Duling Williams Md NPPES
Official registry information on file with the National Plan and Provider Enumeration System.
ALEXA JO DULING WILLIAMS MD (NPI 1972033652) is an individual obstetrics & gynecology provider in O Fallon, Missouri, licensed in Missouri (2021013439) and active in the NPI registry since June 2017. She is enrolled in Medicare PECOS, is affiliated with Ssm St Joseph Health Center, and maintains 2 additional practice locations.
NPPES Registry Identity
Specialties & Licenses
Secondary Practice Locations 2
Group Practice 1
Accepted Insurance
Medicare Participation & PECOS CMS
Medicare enrollment, assignment, billing reassignment, and ordering and referring status from CMS.
Medicare Enrollment Status
Enrolled in Medicare and accepts Medicare assignment
Alexa Jo Duling Williams Md is registered in PECOS and agrees to accept the Medicare-approved amount as full payment. Medicare patients are not billed beyond the standard deductible and coinsurance.
Medicare Billing Reassignments
2Medicare enrollment records show Alexa Williams reassigns Medicare billing to 2 organizations. Each organization bills Medicare for the services this provider delivers there; the nearest is listed first.
O Fallon, MO 63366
- Reassigned Medicare billing, Missouri enrollment
- 697 clinicians in this Medicare group
Wildwood, MO 63040
- Reassigned Medicare billing, Missouri enrollment
- 744 clinicians in this Medicare group
Source: CMS Revalidation Reassignment List, October 2026 release. Reassignment records can lag staffing changes; confirm a current affiliation with the organization.
Areas of Expertise CMS Part B claims
Services this provider delivered to Medicare fee-for-service patients, from the CMS Medicare utilization data. Higher counts generally reflect more experience with a service; care delivered outside Medicare is not included.
Hospital Affiliations CMS Care Compare
Hospitals where this provider delivers care, identified from recent Medicare claims and place-of-service records.
Ssm St Joseph Health Center
Acute Care Hospitals · Saint Charles, MOPhysician Visit Costs CMS claims · ZIP area
Typical Medicare office-visit costs in the 63366 ZIP code area, from fee-for-service claims. These are area statistics, not this provider’s prices; actual charges vary by service and coverage.
Other Providers at the Same Location NPPES 20
Providers registered at the same practice address, or within the immediate area, according to the NPPES registry.
Frequently Asked Questions NPPES & CMS
Common questions about this NPI record, answered from the official NPPES registry and CMS datasets shown on this page.
What is Alexa Williams's NPI number?
The NPI number for Alexa Williams is 1972033652. It was assigned to this individual provider in the NPPES registry on June 15, 2017.
Where is Alexa Williams located?
Alexa Williams practices at 1101 Highway K, O Fallon, MO 63366. The listed phone number is (636) 379-6363.
What is Alexa Williams's specialty?
The primary specialty registered for this NPI is Obstetrics & Gynecology with taxonomy code 207V00000X.
Is Alexa Williams enrolled in Medicare?
Yes. Alexa Williams is registered in the Medicare PECOS system and accepts Medicare assignment, which means accepting the Medicare-approved amount as payment in full for covered services.
Which organizations bill Medicare for Alexa Williams's services?
According to the CMS Revalidation Reassignment List (October 2026 release), Alexa Williams reassigns Medicare benefits to 2 organizations: Ssm Medical Group, Inc. (O Fallon, MO) and Mercy Clinic East Communities (Wildwood, MO). Each reassignment is filed with Medicare on form CMS-855R, signed by both the clinician and the organization, and lets the organization bill Medicare and receive payment for Alexa Williams's services. Reassignment records can lag staffing changes; confirm current arrangements with the organization.
What insurance does Alexa Williams accept?
Health plans from Ambetter Health, Ambetter Health of Delaware, Ambetter from Arkansas Health & Wellness, Ambetter from Sunflower Health Plan and Ambetter of Oklahoma and 4 other insurers list Alexa Williams as in-network in at least one marketplace plan. Coverage varies by plan and year; verify with the insurer or the provider before a visit.
Is Alexa Williams affiliated with any hospitals?
According to CMS data, Alexa Williams is affiliated with Ssm St Joseph Health Center.
When was this NPI record last updated?
The NPPES record for Alexa Williams was last updated on November 10, 2025. NPI Profile syncs weekly with the NPPES registry data releases published by CMS. This NPI record was last updated 11 months ago. If this record has changed at CMS more recently, you can request an on-demand re-check against the live CMS registry, directly from this page.
# Alexa Jo Duling Williams, MD · NPI 1972033652
Obstetrics & Gynecology physician in O Fallon, Missouri. Individual provider, active in the CMS NPPES registry since June 15, 2017.
## Identity
- **NPI:** 1972033652 (Entity type: Individual)
- **Enumerated:** June 15, 2017
- **Primary specialty:** Obstetrics & Gynecology · taxonomy 207V00000X
- **State license:** 2021013439 (Missouri)
- **Sole proprietor:** Yes
## Practice location
- **Address:** 1101 HIGHWAY K, O Fallon, MO 63366-8431
- **Phone:** (636) 379-6363
## Medicare
- **Medicare:** Enrolled (PECOS); accepts Medicare assignment
- **Ordering & referring:** eligible for Part B labs & imaging, durable medical equipment, home health, power mobility devices
- **Bills Medicare through:** 2 organizations under Medicare reassignment (form CMS-855R): Ssm Medical Group, Inc. (NPI 1851896146, O Fallon, MO); Mercy Clinic East Communities (NPI 1164857397, Wildwood, MO) · CMS Revalidation Reassignment List, October 2026 release
- **Medical school:** University Of Arizona College Of Medicine, class of 2017
## Record status
- **NPPES last updated:** November 10, 2025
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Source: [NPI Profile](https://npiprofile.com/npi/1972033652) · Data from the CMS NPPES public registry.